Question

In a Young's double-slit experiment, if the slits are of unequal width.

• A. Fringes will not be formed
• B. The positions of minimum intensity will not be completely dark
• C. Bright fringes will not be formed at the centre of the screen
• D. Distance between two consecutive bright fringes will not be equal to the distance between two consecutive dark fringes

Answer 1

The correct option is B The positions of minimum intensity will not be completely dark

Unequal width of slits will cause unequal intensity of lights entering from both slits.

As a result, during interference complete cancelling of light intensity will not take place at regions of otherwise dark fringe.

As the value of $\beta$ does not depend on intensity of light, there will be no shifting of fringes as well as no change in fringe width.

Answer. B) the positions of minimum intensity will not be completely dark.